[douglas2742]

I have a Flowmaster American Thunder axle back that works with the factory NPP exhaust on my '17 SS. It sounds wonderful and has no drone when cruising thanks to the NPP. I'm thinking of adding the Flowmaster cat back X pipe to the system and was wondering how much louder it is vs. the stock X pipe connected to the Flowmaster axle back. Anybody out there have both the Flowmaster X pipe and axle back? Thank you

[enzia35]

I wouldn't bother with an aftermarket x-pipe unless it deletes the 2nd cats. There are no resonators on the stock x-pipe and the crushed section does not affect flow.

[douglas2742]

Originally Posted by enzia35

I wouldn't bother with an aftermarket x-pipe unless it deletes the 2nd cats. There are no resonators on the stock x-pipe and the crushed section does not affect flow.

It does eliminate the secondary cats and has a more technically advanced X pipe design. Flowmaster is the leader in American muscle car V8 exhaust technology, has been for years. Many disagree and buy the unnecessary higher priced manufacturers, but I think Flowmaster is not only less expensive but superior in development technology. I'll assume it will be a bit louder but still with the deep Flowmaster tone. Most X pipe's for the Camaro deliver a higher pitched, European style sound. But this X pipe was designed to keep the classic Flowmaster sound.

[Abubaca]

Flowmaster is the leader in American muscle car V8 exhaust technology, has been for years.

Is that documented somewhere or just your opinion? ...I for one am not one of the FM haters, and am seriously considering their American Thunder system as well. There's no doubt that the fit and finish isn't on par with some others, and that matters to some. Not so much to others. The main knock on FM comes from the transverse single in dual out 3rd and 4th gen systems. They did NOT flow as well as many others, and back then, there was a good bit to gain replacing the factory system. That of course, and the infamous drone. ...and drone they DID! ....do they now? -don't know. Have no direct experience with the modern FM systems or mufflers. Personally, if the finish was a little nicer, I think it'd be a slam dunk. As it is, I'm still on the fence.


To the OP....I know this isn't exactly what you asked, but at least for my thought process....I was gonna do axle back for now, bump up the sound a notch, and then wait on the aftermarket X and catback pipes for when I do headers.

[shaffe]

Personal experience, but this was over ten years ago. Flowmaster sounds great, but their fit and finish is sub par and the sound is played out. I had an American Thunder system on my Mustang and it sounded good but droned like crazy and started to show rust on parts. The borla system I replaced it with was superior in just about everyway.


Again personal opinion now, but aftermarket X pipe + Flowmaster American thunder yuck! Flowmasters IMO sound horrible with aftermarket X pipes, they lose that flowmaster sound. To me, Flows only sound good with H pipes

[s346k]

Originally Posted by shaffe

To me, Flows only sound good with H pipes

pushrod 5.0 fans die hard, eh. joking aside, i think the mufflers sound good. they’re “played out” bc the design is 40 years old and very popular. i was happy with 3” 1 chambers and an x, it was 1 step from racecar but sounded great. trying to talk dad into doing the same on his el camino. he is using the same fm 40 series dual exhaust i had on a 71 chevelle back in 1999. poor quality? nah...

the good news is these cars have a lot of room back there. just about any muffler you can think of will fit. no need to be on any bandwagon.

[enzia35]

The Flowmaster X-pipes do not delete the 2nd cats unless you do it yourself.

[douglas2742]

Originally Posted by enzia35

The Flowmaster X-pipes do not delete the 2nd cats unless you do it yourself.

Yes it does. Check out the pics on their website. This X pipe was designed specifically for use with the American Thunder axle back. It replaces the entire stock cat back piping that includes GM's x pipe and secondary cats. Installed there is straight through 3" pipes with their unique scavenger x design back to the axle back NPP quad muffler system.

[enzia35]

It doesn't but okay.

[KingLT1]

Originally Posted by douglas2742

Yes it does. Check out the pics on their website. This X pipe was designed specifically for use with the American Thunder axle back. It replaces the entire stock cat back piping that includes GM's x pipe and secondary cats. Installed there is straight through 3" pipes with their unique scavenger x design back to the axle back NPP quad muffler system.

No it doesn't...you have to cut the pipes behind the secondary cats and clamp it. Been covered on this forum previously.

Look at the picture closely. In the pic the left side is what connects to the axle back, the right side is what connects behind the secondary cats.

[breakskeet]

Compare the Flowmaster x pipe to the Corsa, You can clearly see the difference. This one eliminates the secondary cats:

[shaffe]

Originally Posted by s346k

pushrod 5.0 fans die hard, eh. joking aside, i think the mufflers sound good. they’re “played out” bc the design is 40 years old and very popular. i was happy with 3” 1 chambers and an x, it was 1 step from racecar but sounded great. trying to talk dad into doing the same on his el camino. he is using the same fm 40 series dual exhaust i had on a 71 chevelle back in 1999. poor quality? nah...

the good news is these cars have a lot of room back there. just about any muffler you can think of will fit. no need to be on any bandwagon.

haha. I have just never really cared for the sound of a chambered muffler with a X pipe. It just sounds off to me.

They do sound good, but agreed 1000% the sound is played out because everyone and their mother has flowmasters lol.

Now the reason I said poor quality was maybe bc I daily drove my Mustang that had the Flowmaster cat back- through winter. After 1 winter, the clips hangers and all that stuff were starting to rust and the hangers at the base of the exhaust tip were rusting bad enough it was starting to make parts of the tips look rusted.

Switched to Borla and ran that cat back for a couple of years before selling the car and not one spot of rust on the exhaust system

[douglas2742]

[QUOTE=KingLT1;10673863]No it doesn't...you have to cut the pipes behind the secondary cats and clamp it. Been covered on this forum previously.

Look at the picture closely. In the pic the left side is what connects to the axle back, the right side is what connects behind the secondary cats.


Yes, it's the resonators it eliminates. I've heard systems that eliminated the cats and they we're too loud for me.

[enzia35]

Flowmaster posts the instruction online. Go check them out. They do not remove the second cats.
https://www.holley.com/products/exha...pe/parts/81083